Trinidad Head Lighthouse is a lighthouse in United States, in Trinidad Harbor, California. The historic site is located 20 miles (32 km) north of Eureka, California.

History Trinidad Head Lighthouse was built on the Trinidad Harbor in 1871. In 1947, the lens was changed from the fourth order Fresnel lens to a to a 375 mm optic. The lighthouse was automated by the United States Coast Guard in 1974. The low, square, brick tower, painted white, was built in 1871. The light is only 20 feet (6.1 m) above ground, but the headland on which it stands gives it an elevation of 196 feet (60 m) above the sea. The location is one of the most picturesque on the California coast. Despite the great height of the tower above the sea, heavy seas have been known to reach it. In 1913, the keeper made the following report: "At 4:40 p. m. I observed a sea of unusual height. When it struck the bluff the jar was very heavy. The lens immediately stopped revolving. The sea shot up the face of the bluff and over it, until the solid sea seemed to me to be on a level with where I stood in the lantern. The sea itself fell over onto the top of the bluff and struck the tower about on a level with the balcony. The whole point between the tower and the bluff was buried in water." The station originally consisted of the small two-story light tower, a single Victorian residence, and a small barn. In 1898, a bell house was constructed and a 4,000 pound bell was added that was operated by weights. A second keeper was assigned at that time and the quarters were expanded to accommodate two families. In 1947 the fog signal changed to an air horn. The town of Trinidad Head constructed a facsimile of the tower in a park overlooking the harbor and installed the original lens in its structure. The 4,000 pound bell is displayed alongside the tower. In the late 1960s, the Coast Guard razed the original dwelling and barn and constructed the present triplex. The fog signal was discontinued when the station was automated in 1974. However, the complaints from the citizens of Trinidad Head were so vocal that the Coast Guard was forced to install the present ELG 300, operated by fog detector. The new fog signal is operated in the original bell house. The original tower remains basically unchanged.